We present results of an investigation on a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises about 200 G, K, and M stars. Lithium abundances were determined for about 180 G-M stars. Radial velocities were measured for most of the circ. 140 G and K type stars. Combined with proper motions these data were used to study the age distribution and the kinematical properties of the sample. Based on the lithium abundances half of the G-K stars were found to be younger than the Hyades (660 Myr). About 30% are comparable in age to the Pleiades (100 Myr). A small subsample of 10 stars is younger than the Pleiades (100 Myr). They are therefore most likely pre-main sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a group with space velocities close to the Castor moving group but clearly distinct from the Local Association.
@article{arxiv.astro-ph/0408232,
title = {Late-type field stars in the RASS at high galactic latitude},
author = {F. -J. Zickgraf and J. Krautter and S. Frink and J. M. Alcala and R. Mujica and E. Covino and M. F. Sterzik},
journal= {arXiv preprint arXiv:astro-ph/0408232},
year = {2007}
}
Comments
4 pages, 6 figures, to appear in: Proc. 13th Cool Stars Workshop, Hamburg, 5-9 July 2004, F. Favata et al. eds., ESA Special Publications series (ESA SP)